From: Philippe Mathieu-Daudé <philmd@linaro.org>

load_flt_binary() calls load_flat_file() -> page_set_flags().

page_set_flags() must be called with the mmap_lock held,
otherwise it aborts:

  $ qemu-arm -L stm32/lib/ stm32/bin/busybox
  qemu-arm: ../accel/tcg/user-exec.c:505: page_set_flags: Assertion `have_mmap_lock()' failed.
  Aborted (core dumped)

Fix by taking the lock in load_flt_binary().

Fixes: fbd3c4cff6 ("linux-user/arm: Mark the commpage executable")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2525
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240822095045.72643-3-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit a9ee641bd46f5462eeed183ac3c3760bddfc2600)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/linux-user/flatload.c b/linux-user/flatload.c
index 5b62aa0a2b..6278655574 100644
--- a/linux-user/flatload.c
+++ b/linux-user/flatload.c
@@ -747,7 +747,10 @@ int load_flt_binary(struct linux_binprm *bprm, struct image_info *info)
     stack_len += (bprm->envc + 1) * 4; /* the envp array */
 
 
+    mmap_lock();
     res = load_flat_file(bprm, libinfo, 0, &stack_len);
+    mmap_unlock();
+
     if (is_error(res)) {
             return res;
     }
-- 
2.39.5